Former three-time world champion Nonito Donaire believes that Juan Manuel Marquez will win over Mike Alvarado in their upcoming showdown on May 17 at The Forum, which will eventually lead to a fifth showdown with Manny Pacquiao.

In an interview with PhilBoxing, Donaire said that Marquez will score a convincing win against Alvarado by knockout - either with a head or body shot.

Donaire pointed out that the 33-year-old Alvarado is not the same fighter he was during his two epic showdowns with Brandon Rios, citing Alvarado's technical knockout loss to Ruslan Provodnikov in October last year.

"I think Marquez will knock him out with a head or body shot," Donaire said. "Alvarado's not the same fighter anymore. He was badly beaten up by Ruslan and I don't think he'll ever recover from that. He's also not a disciplined fighter."

A Marquez victory will likely lead to fifth showdown between the 40-year-old Mexican and his nemesis, Pacquiao, later this year.

Previous reports indicated that Marquez is interested in becoming a five-division world champion, and is targeting the World Boxing Organization welterweight title, which was recently reclaimed by Pacquiao during his win against Timothy Bradley last month.

And if Pacquiao vs Marquez 5 eventually happens, Donaire confidently said that his compatriot will walk away with a win against the Mexican boxing icon, who knocked Pacquiao out cold during their fourth showdown in December 2012.

"Marquez will beat Alvarado then go on to fight Manny again. This time, Manny will beat Marquez convincingly. Marquez has slowed down a lot and looked old in losing to Bradley. But he should be able to take care of Alvarado," Donaire said.

Pacquiao's trainer, Freddie Roach, echoed the statement of Donaire. The Hall of Fame trainer said that Marquez looked old during his fight against Bradley, but Roach thinks that Marquez will be able to handle Alvarado.

Roach is also confident that they will be able to convince Marquez to fight Pacquiao, and the 53-year-old trainer predicted a victory for his prized fighter, saying that Pacquiao is a much smarter fighter now that what he was during his fourth fight with Marquez.

"They know each other so well. This time, Manny will win decisively. Manny's a much smarter fighter now," Roach said.